Lubricants for high-load mechanisms



United States Patent 3,117,932 LUERICANTF; 536R HlGH-LOAD MEQHANESMS Lucien Yras, Billancourt, France, assignor to Regie Nationale des Usines Renault, Biiiancourt, France No lBrar-vinga Filed 0st. 27, 1959, Ser. No. 848,892 Claims priority, application France Nov. 21, 1958 2 Claims. (Cl. 252-546) This invention relates to lubricants and has specific reference to lubricants intended for mechanisms wherein the prevailing temperature and pressure conditions are such that it is not possible to have an oil film maintained by hydrodynamic forces between the rubbing metal surfaces, and for which the oiliness, that is, the aptitude of a lubricant to adhere to the metal without corrosion, under moderate pressures is preserved when the temperature attains values considerably higher than those which could not safely be overstepped heretofore with hitherto known products, these lubricants providing the desired seizureresisting characteristic under very high pressures at which the oiliness is no more available.

A considerable advancement was achieved by the applicant in the development of universal lubricants, that is, capable of preserving their oiliness and an oily film under moderate pressures and/ or temperature, and avoiding the seizure of parts in mutual frictional contact when the loads or relative sliding motions are considerable, by adding to mineral oils long-chain fatty esters associated with esters of tetrachlorolauric acid. However, the trend of modern techniques has led to mechanisms operating under extremely variable load and speed conditions.

Since it becomes increasingly necessary to extend the 3,117,932 Patented Jan. 14, 1954 The methyl or ethyl pentachlorobutyrates are obtained, as already known, by esterifying directly the pentachlorobutyric acid with methyl or ethyl alcohol saturated with hydrochloric gas.

The novel properties of the lubricant according to this invention are evidenced by laboratory tests carried out With the Boerlage four-ball testing machine 1 for tests under extreme pressure conditions and with the Herschell testing machine for oiliness tests. With the assistance of this last-mentioned machine, the coeflicients of friction are determined with average contact pressures of 21,330 psi. (15 kg./sq. mm.) by means of tests comprising the driving of three balls solid with a same member by a metal disc rotating in its plane about its axis. The driving torque applied to the balls, proportional to the coeflicient of friction, is measured against the reaction torque of a spiral spring.

When the measuring assembly is wetted with pure mineral oil, there is no stable position of the pointer connected to the antagonistic spring. A rapid sequence of alternate dry-contact drives and lubricated frictional contacts is observed. The friction becomes stable when the oil contains either a fatty ester or the mixtures according to this invention, but in the first instance the stability ceases at a temperature lower than in the second case.

By way of illustrative example to show the novel advantages characterizing this invention, there is summarized in Table I hereafter the resistance to seizure of the mixtures according to this invention as evidenced by measurements made with the Boerlage testing machine, wherein the pressure ranges from 355,500 to 711,000 p.s.i. (250 to 500 kg./sq. mm.).

Table 1 Mineral Mineral 011 1% oil 1% Mineral Mineral Pure Good pentachlord pentachlorooi1+ 1% oil .5% mineral commcre. bntyrate butyrate methyl stcaric oil EP-oil 1% methyl .5% stearic stearatc acid stearate acid Max. load without seizure:

8O 80 70 (it) 60 90 1, 760 1, 760 1, 540 1, 320 1, 320 2, 000

From the foregoing it appears clearly that the addition limits set up by these adverse conditions of operation, it is also desirable to provide lubricants having an increasingly wider field of practical application.

With the lubricant according to this invention frictional contacts without seizure under loads as high as those permitted by the best commercial extreme pressure oils can be effected, and moreover, under reliable oiliness conditions a very low coeficient of friction can be obtained. Finally, this improved lubricant has very low corrosive characteristics with respect to the steel parts of the mechanisms.

This invention is concerned with a new lubricant composition which is obtained by adding to known lubricating oils quantities ranging from .2% to 3.0% of the methyl or ethyl ester of a pentachlon'nated butyric acid, which constituted the subject-matter of former researches by the applicant, and wherein the position of the chlorine atoms corresponds to the following formula:

This addition is utilized together with fatty acids and long-chain fatty esters and notably the stearic, palmitic, and behenic acids as well as the methyl, ethyl, propyl and isopropyl esters of the same acids, in quantities of from .O5% to 2.0%.

of methyl petanchlorobutyrate to mineral oils, in combination with the stearic acid or methyl stearate, improves considerably their resistance to seizure and impart to the lubricant extreme pressure properties similar to those of the best commercial products.

But what is remarkable is that these new lubricants are characterized not only by good extreme pressure properties but also by a remarkable oiliness whereby the values of the coeflicient of friction undergo but a very moderate dispersion in time, the latter having on the other hand a very low mean value, a property not found in any of the commercial extreme pressure oils.

Table II hereafter shows the coefiicients of friction and the values of the average quadratic discrepancies with respect to the mean values of the coefiicient of friction,

References concerning the four-ball testing machine- Clayton, Engineering 149, 131 (1940). Block, Journal of the Society of Petroleum, 44, 193 (1939). Nest, Journal of the Institute of Petroleum, 32, 206 (1946).

3,1 3 determined by means of the Herschell testing apparatus at different temperatures with the following mixtures:

Percent Pure Vaseline oil 93 (1) Methyl pentachlorobutyrate 1 Methyl stearate 1 Vaseline oil 98.5

(2) Methyl pentachlorobntyrate 1 [Stearic acid .5

(3) Pure Vaseline oil. (4) 5% commercial extreme pressure additive in pure Vaseline oil.

The coeificient of friction remains extremely low in the case of mixture 1 and very low in the case of mixture 2, even at temperatures as high as 115 C., as contrasted with mixtures 3 and 4 showing a relatively high coefficient of friction value and a high degree of dispersion even at ordinary temperature.

On the other hand, mixture 2 is characterized by a complete absence of corrosiveness even under very severe conditions of operation.

The new lubricants are particularly useful for lubricating internal combustion engines during the running-in period, and also for the permanent lubrication of transmission members, gearbox pinions, bevel gears, etc. inasmuch as the risk of corrosion is extremely low with these lubricants.

Moreover, they reduce considerably the rate of wear and increase the efficiency by reducing the coeflicient of friction between sliding surfaces.

As the development of heat by rubbing is reduced, the temperature of operation of the lubricant remains moderate and the thermal alteration is kept to a very low value. The useful life of this lubricant is considerably longer mesa than that of ordinary oils not improved by the components according to this invention.

1 claim:

1. A lubricant eifective to maintain between two sliding surfaces the necessary lubricating film under pressure and temperature conditions wherein the maintainance of this film is not ensured by hydrodynamic forces, and effective to provide resistance to seizure under very high pressures and very high corrosion-resisting properties with respect to metal, said lubricant comprising a major proportion of mineral oil, 0.2 to 3% by weight of at least one compound selected from the group consisting of the methyl and ethyl esters of pentachlorobutyric acid of the formula Cl CCI-IClCI-IClC0OH, and 0.05 to 2% by weight of at least one long-chain fatty compound selected from the group consisting of long-chain fatty acids and the methyl, ethyl, propyl and isopropyl esters thereof.

2. A lubricant effective to maintain between two sliding surfaces the necessary lubricating film under pressure and temperature conditions wherein the maintainance of this film is not ensured by hydrodynamic forces, and effective to provide resistance to seizure under very high pressures and very high corrosion-resisting properties with respect to metal, said lubricant comprising a major proportion of mineral oil, 0.2 to 3% by weight of at least one compound selected from the group consisting of the methyl and ethyl esters of pentachlorobutyric acid of the formula Cl C CHCl-CHCl-COOH, and 0.05 to 2% by weight of at least one long-chain fatty compound selected from the group consisting of palmitic acid, stearic acid, behenic acid, and the methyl, ethyl, propyl and isopropyl esters thereof.

References Cited in the file of this pater UNITED STATES PATENTS 2,210,140 Colbeth Aug. 6, 1940 2,812,307 Saives Nov. 5, 1957 2,877,182 May Mar. 10, 1959 FOREIGN FATENTS 540,031 Canada Apr. 23, 1957 784,876 Great Britain Oct. 16, 1957 OTHER REFERENCES Ellis: Lubricant Testing, 1953, Scientific Publications (Great Britain) Ltd., pp. 148-150 pertinent. 

1. A LUBRICANT EFFECTIVE TO MAINTAIN BETWEEN TWO SLIDING SURFACES THE NECESSARY LUBRICATING FILM UNDER PRESSURE AND TEMPERATURE CONDITIONS WHEREIN THE MAINTAINANCE OF THIS FILM IS NOT ENSURED BY HYDRODYNAMIC FORCES, AND EFFECTIVE TO PROVIDE RESISTANCE TO SEIZURE UNDER VERY HIGH PRESSURES AND VERY HIGH CORROSION-RESISTING PROPERITES WITH RESPECT TO METAL, SAID LUBRICANT COMPRISING A MAJOR PROPORTION OF MINERAL OIL, 0.2 TO 3% BY WEIGHT OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE METHYL AND ETHYL ESTERS OF PENTACHLOROBUTYRIC ACID OF THE FORMULA CL3C-CHCL-CHCL-COOH, AND 0.05 TO 2% BY WEIGHT OF AT LEAST ONE LONG-CHAIN FTTY COMPOUND SELECTED FROM THE GROUP CONSITING OF LONG-CHAING FATTY ACIDS AND THE METHYL, ETHYL, PROPYL AND ISOPROPYL ESTERS THEREOF. 